Alternative formats

This paper presents a review of all patients with Down syndrome seen over a 5-year period by one consultant neurologist in general outpatient and specialist cognitive function clinics. It revealed only 7 cases in > 4500 general referrals (= 0.2%), all referred with suspected seizure disorders. The diagnosis of epilepsy was confirmed in 6 patients. Only one new, comorbid, diagnosis was made. Neurologists have little exposure to, and hence little chance to develop expertise in, the neurological complications of Down syndrome. It is suggested that closer liaison between neurologists and psychiatrists with an interest in learning disability might improve the management of neurological problems in patients with Down syndrome.

Down syndrome, the most common chromosomal abnormality, may be associated
with a variety of neurological complications including epileptic seizures,
stroke (perhaps related to congenital heart disease), cervical spinal cord
compression (related to atlanto-axial joint anomalies), and basal ganglia
damage[1]. In addition, all patients with Down syndrome develop Alzheimer's
disease-like neuropathology, sometimes associated with the clinical correlate of
dementia[2-4]. For these reasons, one might anticipate that patients with Down
syndrome would be encountered in neurology outpatient clinics. However, prior
studies of the frequency and/or utility of neurological consultation for
patients with Down syndrome have not been identified.

Materials and methods

Records of the author's general neurology outpatient clinics based in two
district general hospitals (DGH) and a regional neuroscience center, and special
interest Cognitive Function Clinic based in the regional neuroscience center,
were examined for the 5-year period 2002-2006 inclusive to identify
consultations with patients with a diagnosis of Down syndrome. Referral source,
indication for referral, neurological diagnosis or diagnoses, and outcome were
noted for all cases. No cases with unspecified causes of learning disability,
nor cases with other defined chromosomal abnormalities[5], were included.

Results

Of 4590 new patient consultations seen in general neurology outpatient clinics
over the 5-year study period, there were 8 new consultations with patients with
Down syndrome (= 0.2%); all were seen in DGH clinics. The number of patients
with Down syndrome seen ranged from 0-3 per year. Of 436 new patients assessed
in the Cognitive Function Clinic, none had Down syndrome.

The 8 Down syndrome patient episodes (TABLE 1) involved 7 different patients
(one patient was referred twice during the study period; M:F = 5:2, age range
31-52 years, median age 46.5 years). All referrals were made by the patient's
general practitioner. Three patients were already under the care of a
psychiatrist with an interest in learning disability. Three patients were in
residential care establishments; the others were living at home, sometimes with
additional care support.

All patients were referred because of episodes of impaired consciousness which
their general practitioners suspected to be due to epilepsy. Four patients were
already receiving anti-epileptic drugs (AEDs) at the time of referral. Three
patients already had a diagnosis of dementia, although none were receiving
cholinesterase inhibitors or memantine. No patient attended alone; all came with
a relative or carer or both, although in one case the carer had not witnessed
any of the episodes of impaired consciousness and so was unable to provide any
useful collateral history.

As a consequence of neurological consultation, six of the patients were judged
to be suffering epileptic seizures; in the other patient loss of consciousness
was thought to be due to a syncopal episode.

In three of the patients diagnosed with epilepsy, the clinical features were
consistent with a syndromic diagnosis of late-onset myoclonic epilepsy in Down
syndrome (LOMEDS)[6-7]; two of these patients already had evidence of dementia.

In one of the patients with epilepsy, a concurrent diagnosis of obstructive
sleep apnoea-hypopnoea syndrome (OSAHS) was suggested. This condition, which may
present initially in neurology clinics[8], may cause or exacerbate epileptic
seizures. The diagnosis was later confirmed using nocturnal pulse oximetry
studies performed by a chest physician with an interest in OSAHS. This was the
only new diagnosis established as a consequence of neurological consultation.

Discussion

The very small number of patients with Down syndrome identified in this 5-year
review of general and specialist cognitive neurological practice prompts a
number of questions, specifically, are these numbers more or less than one might
expect, and are referrals occurring too late?

Few, if any, neurologists will have any specific training, far less any
expertise, in the management of patients with Down syndrome, in which case any
referral of a patient with Down syndrome to the neurology clinic might be deemed
surprising, given the dictates of clinical governance. The numbers seen in this
survey are similar to those of the most common Mendelian monogenic disorders
seen in general neurology clinics (i.e. Huntington's disease, neurofibromatosis
type 1)[9], and are likewise far too small to permit the development of any
management expertise. It may be cogently argued that patients with Down syndrome
are best managed in a dedicated special interest clinic.

However, in view of the possible neurological complications of Down syndrome[1],
these numbers might be deemed too small. Considering specifically the diagnosis
of epilepsy, which was the indication for referral of all the patients seen in
this survey, guidelines have previously been published suggesting a model of
epilepsy care which includes subspecialty clinics to meet the needs of patients
with epilepsy in learning disability[10]. Such provision may be required because
insufficient neurological expertise is deemed available in dedicated learning
disability clinics. The correct diagnosis of late-onset seizures in Down
syndrome is crucial since this may herald onset of cognitive decline[11,12], in
the same way that seizure onset concurrent with the development of Alzheimer's
disease has been documented in the non-Down syndrome population[13], and hence
be a marker for consideration of anti-dementia drug therapy. Such medications
have been investigated in Down syndrome[4], and although their exact place in
management remains to be defined, it would seem likely that their greatest
benefit will be in early cognitive decline. Hence it might be argued that
referring patients with Down syndrome with an established diagnosis of
late-onset epilepsy and already receiving anti epileptic drugs is too late,
since the most appropriate time to commence anti-dementia drug therapy is
already passed.

Greater communication between psychiatrists with an interest in learning
disability and neurologists, perhaps even joint clinics[14] may be required for
the optimum management of neurological problems in Down syndrome.

Online stores

Down Syndrome Education Organisations

DSE works to improve education and early intervention for children with Down syndrome.
Our research and evidence-based services and resources are helping thousands of young people with Down syndrome to achieve more than ever before.

With your support, we can accelerate research, develop new services and resources, and provide support and advice to more families and professionals everywhere.